Reflector target



Jan. 15, 1957 N. N. LEONARD REFLEEETOR TARGET Filed Aug. 10. 1953 3Sheets-Sheet l N. NELSON Jan. 15, 1957 N N. LEONARD REFLECTOR TARGETFiled Aug. 10, 953

5 Sheets-Sheet 2 I/vvENToIe N NELso/v LEONAPD ATTQENE Y- Jan. 15, 1957N. N. LEONARD REFLECTOR TARGET 3 Sheets-Sheet 3 Filed Aug. 10, 1953ZNVENTOIE 4V. NELSON L ONARD REFLECTOR TARGET Nathaniel Nelson Leonard,West Los Angeles, Calif., assignor to (Zlaude C. Slate & Associates, LosAngeles, Calif., a copartnership Application August 10, 1953, Serial No.373,134

1 Claim. (Cl. 34318) This invention relates to reflector targets of thetype employed in the operation of radar equipment such as is used by theCoast Guard in spotting objects at sea (e. g. lifeboats or rafts orother small boats).

The invention has as its general object to provide a reflector targetthat may be used by a small boat or raft in distress, to facilitate searescue operations. More specifically, the invention aims to provide areflector target that will return a radar signal of higher gain than canbe obtained from a lifeboat or raft, thereby greatly increasing therange of radar search equipment.

An improved design for such a target is one that pre sents amultiplicity of plane reflecting surfaces disposed in three planes eachat right angles to both of the others, intersecting at a common centerand presenting a series of trihedral-angular reflector. cavities, eachof equi-lateral, inverted pyramid form. More specifically, in thecommonly accepted form of such device, the reflector surfaces of thethree respective planes are shaped so that the reflector areas of thethree planes are square, and so that their peripheral edges collectivelydefine the edges of a regular or equi-lateral tetra-hedron. In such adevice, there are eight of the outwardly flaring, trihedral reflectorcavities, with the axes of the cavities radiating, at equal angulardisplacements one from the other, in all directions from the commoncenter of the device, and because of the relationship between the anglesof incidence and reflection of a radar beam intersecting the target atany point within its total volume, there will always be at least one ofsaid beams reflected directly back to the source of the beam.

The primary object of the present invention is to provide a suitableconstruction and arrangement of the pants of a target of this type,whereby the target may be readily collapsed into a package of minimumbulk. The most difficult problem that has been encountered in attemptsto provide a collapsible target, is that of avoiding difficulties thatbe experienced by a person attempting to assemble or expand the targetfrom a folded or collapsed condition to its functional configuration. Asto this problem, tests that have been made upon earlier targets such asthose mentioned above, and other previously proposed designs forfoldable targets, have indicated complete unsuitability of such devicesfor use by inexperienced persons or persons not possessing a fairly highdegree of mechanical ingenuity. However, a basic requirement of a targetfor use in cases of distress at sea, is that the person in distressshall be able to assemble or manipulate the target to its expanded,functional form without difficulty, regardless of whether he ispossessed of mechanical ingenuity or not.

Targets of the foldable type as previously utilized have been made inthree separate panels, notched in such a manner that they will fittogether to form the configuration previously described and fastenedtogether by cords tied through each of the six corners. These targetshave been found extremely difficult to assemble even by experiitedStates Patent O enced personnel under favorable conditions. Otherreflector targets of a different type are available but they cannot becollapsed into a satisfactorily small compact package.

With the foregoing in mind, a primary object of the present invention isto provide a suitable construction and arrangement of the parts of atarget of this type, whereby the target may be collapsed into a packageof minimum bulk and yet may be assembled or unfolded by inexperiencedpersons under adverse conditions.

The problems of folding could of course be avoided by utilizing anon-collapsible target. However, because of the large ratio betweentotal volume and solid bulk, freight rates for such a device would be ata maximum scale. Furthermore, the problems of storage, transportation,handling and protection against damage, would rule out the use of anon-collapsible target. The need for a fully collapsible target will beapparent from the foregoing.

The provision of a construction whereby a target may be readilycollapsed into a compact package, engenders other problems in additionto the one mentioned above. To provide a target that can be easilyexpanded to its functional form, its reflecting panel sections must notonly be movable relative one to another, but must be provided with meansfor connecting them together in a manner to permit of relative movementbetween them such that they can be folded flatly one against another.Such folding process should preferably be guided by the construction ofthe target, so that the proper folding of the sections is not left toguess work or the vagaries of individuals who may be handling thetarget. The connections between the sections should preferably be suchas to require minimum of manipulation by the operator. On the otherhand, the connections should be such that when the target is expanded toits operative shape, the several sections are securely attached one toanother, with the entire assembly being relatively rigid. Furthermore,the connecting means should be such that the several sections areaccurately disposed in their respective positions, with a minimum oferror in the equi-angular relationship between the reflector surfaces.Not the least in importance is the need for attaining the abovementioned characteristics in a relatively simple and inexpensive yetsturdy construction. This is a primary object of the invention.

Toward the attainment of the above stated objects, the invention, ingeneral, contemplates a target having a plurality of reflector panelsections hinged together and connected by a harness of cords adapted,when pulled, to completely effect the movement of the panel sectionsfrom folded to expanded positions. In the early attempts to achieve suchan arrangement, however, difliculty was experienced with tearing thepanel sections apart where too much pull was applied to the harnesscords. A further object of the invention is to provide an arrangementsuch that all forces resulting from the pull of the harness cords, areabsorbed by the panel sections without being imposed upon the hinges orbetween laminations or other parts subject to separation.

Other objects will become apparent in the ensuing specifications andappended drawings in which:

Fig. l is a front elevational view, slightly in perspective, of thetarget fully expanded and in a normal position for use;

Fig. 2 is a fragmentary side elevational view of the same;

Fig. 3 is a fragmentary horizontal sectional view of a corner portion ofthe same taken on the line 3-3 of Fig. 2;

Fig. 4 is a side elevational view of the target, illustrat- PatentedJan. 15, 1957 ing an early stage in the folding of the quarter sectionsthereof;

Fig. 5 is a fragmentary front elevational view of the target in the sameposition of partial folding;

Fig. :6 is a fragmentary horizontal sectional view of the centralportion of the target, taken on the line -66 of Fig. 4;

Fig. 7 is a detail vertical sectional view of the upper corner of thetarget, taken on the line 'l7 of Fig. 4;

Fig. 8 is a front elevational view, slightly in perspective,illustrating the target in a final stage of folding; and

Fig. 9 is a front elevational view of the fully folded target.

Referring now to the drawings in detail, my improved folded radar targetcomprises a plurality of panel members, each having reflecting surfaceson both faces thereof, said panel members being arranged, in the fullyexpanded target, so as to provide three square, equal refiector areasdisposed in respective planes intersecting one another at right anglesat a common center, the three areas being generally designated A, B andC respectively. The respective reflector areas are provided respectivelyby:

' A. A single square panel, individually providing one of said squarereflector areas. This square panel, which will be hereinafter referredto as the base panel, and which is designated (a), is, in those views(Figs. 1, 4 and 9) which are designated as front elevational viewsviewed generally edgewise, i. e., as lying generally in the line ofsight.

B. A pair of half panel sections of right triangular shape, eachproviding one half of the square reflector area B, and lying generallyat right angles to the line of vision in the above mentioned frontviews. For convenience in referring to them, these half-area panelsections (left and right respectively, as viewed in Fig. 1) aredesignated b1 and b2 respectively. Each of the sections b1, b2 is hingedalong its hypotenuse to the vertical, medial axis of panel .A, indicatedat y. The folding ,of the panel sections [21, b2 therefore takes placewith a horizontal movement around the y-axis, .as indicated by the arrow30 in Fig. 8.

C. Four quarter panel sections, of equilateral, right triangular shape,each providing one quarter of the C area, said quarter sections beingdesignated 01, c2, c3 and 04 respectively, for convenience in furtherreference thereto (see Fig. 4). These four quarter sections are hinged,in pairs, to the respective half sections b1 and 12,2, along ahorizontal hinge axis indicated at z. Thus, as is plainly illustrated inFig. 4, these quarter sections cl-c4, in folding, are moved verticallyabout the z axis.

It will be noted that in the case of the quarter sections 01-04, thehinge axis occurs .at one of the equilateral sides of each section, theother equilateral side being arranged closely adjacent and parallel to arespective face of the base panel (a) and, in the fully expanded target,the free sides being arranged along the horizontal axis designated x, atright angles to the z axis.

The above referred to x, y and z axes, in the fully expanded target, arearranged each at right angles to both of the others, and intersect oneanother at the center of the target.

The marginal edges of the panel members (a), b1, b2, cl-c4 are locatedas the edges of a regular octahedron, i. e., one having eight sides eachhaving the shape of an equilateral triangle.

Referring now to Figs. 3, 6 and 7, the panel (a) is fabricated, inlaminated form, from a body sheet of heavy cardboard, laminated wood,plastic material or other suitably stiif sheet material, indicated at10, and is faced with reflective facings 11 which consist in thin sheetsof alumimm or tin foil adhesively attached to body sheet 10, or may beconstituted by coatings of electrical conducting material such ascolloidal silver paint or electro deposited metaLsuitably applied in athin film by known methods.

4 Similarly, half sections b1, b2 are fabricated from body sheets 10bhaving reflective facings 11b on the respective faces thereof.Similarly, quarter panel sections C1-C4 (Fig. 3) are fabricated frombody sheets 10c covered with reflective facings 110. In each case, themargins of the panel members are reinforced and protected by marginbindings 12 of channel shape, adhesively secured to the marginalportions of the facings 11, 11b, 11c and embracing the same. Suitablematerial for the bindings is book-binding buckram, in tape form. Similarmaterial may be utilized to provide hinges 13b, 130, the hinges 13bconnecting panel sections b1, b2 to base panel (a) along axis y, andhinges 13c connecting quarter sections 01-04 to base panel (a) alongaxis z.

Along the axis x, the inner lateral margins of sections 01-04 are inclosely spaced, parallel relation so that each pair of sections (c1 and02 on one side, and c3 and 04 on the other side) defines a narrow slotin which a respective half panel section b1, b2 is respectivelyreceived. Since the other lateral margins of the quarter sections areattached, by hinges 130, to "base section (a), the opposed, slotdefining margins of sections 01-04 will be securely held in thisparallel, closely spaced relation, and will abut the half sections b1,122 to firmly support the latter in a common plane constituting thebisector of and normal to areas A and C. This will be true as long asthe quarter sections c1c4 are disposed in a plane normal to axis -y. Byfolding the quarter sections c1c4 flatly against the base panel (a), thehalf sections b1, b2 are released for folding movement around axis y, topositions folded flatly against the infolded quarter sections 01-04, asillustrated in Fig. 9.

In order to attain maximum compactness in the folded target, the quartersections are preferably folded in the directions indicated in Fig. 4,one of each pair being folded downwardly and the other of each pairbeing folded :upwardly, although it is possible to fold the sections ofone pair downwardly and the other pair upwardly, ,or even to fold allquarter sections in a common direction, either upwardly or downwardly.

The invention is particularly characterized by a harness comprising anarrangement of pull cords d1, d2, d3, d4 which at their ends areattached to eyelets 14, 14' in the free corners of .the respectivequarter sections 01, c2, c3, 04; are passed through eyelets 15, 15 inthe lateral corners of half sections; and are thence passed througheyelets 16, 16' in the upper corners of the half sections b1, b2.

The ends of cords a1, a2 are joined by a loop 17 and the ends of cordsa3, a4 are joined by a loop 17'. In the fully extended target, the loops17, 17, attached to a suitable support (e. g. a mast, oar, boat hooketc), will function as a leader for attaching the target to the supportand suspending it therefrom.

A pull of adequate intensity against the lower end of the target may beprovided for by employing, as a handle, a loop 27 which isattached toeyelets 28 in the lower corners of half sections b1, b2.

The harness 01, c4 is particularly arranged so as to execute thefollowing functions: (1) by simply grasping the tips of loops 17, 17which, in the fully folded target are relatively close to the apex ofthe target as shown in Fig. 8, and pulling them upwardly while applyinga downward pull to the lower end of the target, a pull will betransmitted to the outer corners of the respective quarter panelsections c1-c4, such as to draw them toward the plane .of area Cof theassembled target of Fig. 1, as indicated by the arrows 26 of Fig. 4. Asthe quartersections 01-04 thus move toward the plane of area C, theywill engage and move the half sections b1, b2 to the plane of area B.(.2) When the quarter sections c 1.- c4 have arrived at the plane ofarea C, further pull on the harness willfunction to hold them securelyin that plane.

The e functions are obtained through the arrangement whereinieach cordis attached atone end to an outer (free) corner of a respective quarterpanel section, is thence passed through the respective eyelet 15, or tothe opposite side of the adjacent half panel section b1 or b2 from theside on which it is attached to the quarter section, is extended alongsaid opposite side from the respective eyelet 15 or 15 to the respectiveeyelet 16 or 16, and is thence passed through the latter eyelet on thesame side of the respective half panel section b1 or b2 as the side onwhich it is attached to the quarter panel section, where it becomes aportion of a respective loop 17 or 17. It will now be apparent that therespective portions of loop 17 or 17' are passed in opposite directionsthrough the same eyelet 16 or 16' to become respective cords of a pairof cords d1, d2 (or d3, d4, as the case may be); are then extended in aparallel relation along opposite sides of a respective half panelsection b1 or b2, are then extended in opposite directions through acommon eyelet 15 or 15', and are then attached to the corners of arespective pair c1, 02 (or c3, c4) of quarter panel sections.

In the folded target, each of the cords d1d4 extends from a respectiveloop 17 or 17' through a respective eyelet 16 or 16, is thence extendeddownwardly along one side of a respective half section b1 or b2, -isthence extended through an eyelet 15 or 15' and thence extends upwardly(or downwardly) to the free corner of the respective quarter section asindicated in Fig. 8. In opening the target to fully extended condition,the last mentioned portions of the cords, extending upwardly (ordownwardly) from the eyelets 15, 15 to the free corners of the foldedquarter panel sections, are drawn through the eyelets 15, 15 until thepoint of attachment of the cord to the corner of the respective quartersection is directly opposite the respective eyelet 15, 15. At thispoint, no more cord can be drawn through the eyelets 15, 15, andaccordingly the pull on the cords firmly holds the free corners of thequarter panel sections directly opposite the respective eyelets 15, 15,i. e., in registration with the lateral corners of the respective halfpanel sections b1, b2.

In folding the target, the harness is released so that the various cordsare free to draw through the eyelets 15, 15, 16, 16'; the base panel (a)is suitably held; and the four quarter panel sections c1c4 are thenfolded against their respective sides of main panel (a), in. directionsopposite to those indicated by arrows 26, until they are flatly foldedagainst panel (a). In this folding operation, the cords d1d4 will bedrawn through eyelets 15, 15', 16, 16 and only the short loops 17, 17'will remain projecting beyond the apex of the target. The half sectionsb1 and b2 are then folded in opposite directions against the respectivesides of the base panel (a), as indicated by arrow in Fig. 8, to bringthe target to the flatly folded, compact package form shown in Fig. 9.The folded target may then be placed in a suitable pouch or envelope,until ready for use.

It will now be apparent that the folded target can be expanded tooperative form simply by grasping the cords d1-d4 in one hand and theloop 27 in the other hand and moving the hands apart to impose a pullbetween the cords and the loop. This can be executed by any person oflimited mechanical ingenuity, and in only a second or a few seconds oftime.

An important characteristic of the invention is the arrangement of theharness so that the tension forces in cords d1-d4 are transmittedthrough eyelets directly into half panel sections b1, b2, and thencelongitudinally through half panel sections b1, b2 to loop 27 withoutbeing imposed upon hinges 13b, 130 or set up between laminated parts 10,11, 12 etc.

I find that with the construction shown, wherein loop 27 is attached tothe lower corners of half sections b1, 122 through eyelets 28, whereincords dl-d4 are threaded through eyelets 15, 15', 16, 16' in sectionsb1, b2 and are attached to quarter sections c1-c4 through eyelets 14,14, that loads of several hundred pounds can be transmitted through thetarget between the cords and the loop 27 without de-laminating, tearingout the eyelets, pulling apart the hinges, or otherwise damaging thetarget.

I claim:

In a collapsible reflector target: a plurality of panel members eachhaving reflector surfaces on both faces thereof, said panel members, inthe expanded target, occupying three equal areas of square form disposedin planes each intersecting both of the others at right angles alongaxes of intersection each constituting a common median diagonal axis oftwo of the areas; said panel members comprising a single square basepanel coextensive with one of said areas, a pair of isoceles righttriangular half panel sections having hypotenuse margins hinged toopposite sides of said base panel along a first one of said mediandiagonal axes thereof and together constituting another of said areas,and four isosceles right triangular quarter panels arranged in pairseach having respective side margins hinged to opposite sides of arespective half panel section along a second one of said median diagonalaxes and having free side margins arranged to abut respective faces ofsaid base panel along the third one of said median diagonal axes and tothereby brace said half panel sections to maintain their respectiveplane normal to the plane of said base section, said quarter panelsections being adapted for hinging movement around said second axis topositions folded in face-to-face engagement with the respective halfsections to which they are hinged, with said free side marginssubstantially registering with said first axis, whereby to allow saidhalf panel sections to be folded about said first axis to positions insubstantially face-to-face relation to said base panel, whereby thetarget becomes fully collapsed; and means for expanding the target fromsaid fully collapsed condition to a fully open condition, comprisingmeans to anchor one corner of said base panel at one end of said firstmedian diagonal axis means defining a pair of apertures in the oppositecorner of the base panel on opposite sides of said first axis, meansdefining a lateral aperture in each of the other two corners of saidbase panel, and a harness comprising a plurality of cords each attachedto the free corner of a quarter section, passing through a respectiveone of said lateral apertures thence extended to said opposite corner ofthe base panel and passing through one of the apertures therein, thecords of opposed quarter panel sections on opposite sides of the basepanel being passed in opposite through a common lateral aperture andagain through a common one of said pair of apertures, with all of saidcords extending away from the target along an extension of said firstaxis, whereby all quarter sections may be simultaneously moved towardtheir open positions by exerting a common pull against all cordssimultaneously in opposition to said anchor means.

References Cited in the file of this patent UNITED STATES PATENTS2,419,549 Griesinger Apr. 29, 1947 2,475,633 Morris July 12, 19492,498,660 Dunmore Feb. 28, 1950 FOREIGN PATENTS 466,670 Canada July 18,1950 658,915 Great Britain Oct. 17, 1951

